Messages in this thread Patch in this message | | | From | Jane Wan <> | Subject | [PATCH v4 2/2] mtd: rawnand: use bit-wise majority to recover the contents of ONFI parameter | Date | Tue, 8 May 2018 14:19:54 -0700 |
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Per ONFI specification (Rev. 4.0), if all parameter pages have invalid CRC values, the bit-wise majority may be used to recover the contents of the parameter pages from the parameter page copies present.
Signed-off-by: Jane Wan <Jane.Wan@nokia.com> --- drivers/mtd/nand/raw/nand_base.c | 49 ++++++++++++++++++++++++++++++++++---- 1 file changed, 44 insertions(+), 5 deletions(-)
diff --git a/drivers/mtd/nand/raw/nand_base.c b/drivers/mtd/nand/raw/nand_base.c index 72f3a89..dfc341c 100644 --- a/drivers/mtd/nand/raw/nand_base.c +++ b/drivers/mtd/nand/raw/nand_base.c @@ -5086,6 +5086,38 @@ static int nand_flash_detect_ext_param_page(struct nand_chip *chip, return ret; } +#define GET_BIT(bit, val) (((val) >> (bit)) & 0x01) + +/* + * Recover NAND parameter page with bit-wise majority + */ +static int onfi_recover_param(struct nand_onfi_params *p, int pages) +{ + int i, j, k; + u8 v, m; + u8 *buf; + + buf = (u8 *)p; + for (i = 0; i < sizeof(*p); i++) { + v = 0; + for (j = 0; j < 8; j++) { + m = 0; + for (k = 0; k < pages; k++) + m += GET_BIT(j, buf[k*sizeof(*p) + i]); + if (m > pages/2) + v |= BIT(j); + } + ((u8 *)p)[i] = v; + } + + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)p, 254) == + le16_to_cpu(p->crc)) { + return 1; + } + + return 0; +} + /* * Check if the NAND chip is ONFI compliant, returns 1 if it is, 0 otherwise. */ @@ -5102,7 +5134,7 @@ static int nand_flash_detect_onfi(struct nand_chip *chip) return 0; /* ONFI chip: allocate a buffer to hold its parameter page */ - p = kzalloc(sizeof(*p), GFP_KERNEL); + p = kzalloc((sizeof(*p) * 3), GFP_KERNEL); if (!p) return -ENOMEM; @@ -5113,21 +5145,28 @@ static int nand_flash_detect_onfi(struct nand_chip *chip) } for (i = 0; i < 3; i++) { - ret = nand_read_data_op(chip, p, sizeof(*p), true); + ret = nand_read_data_op(chip, &p[i], sizeof(*p), true); if (ret) { ret = 0; goto free_onfi_param_page; } - if (onfi_crc16(ONFI_CRC_BASE, (uint8_t *)p, 254) == + if (onfi_crc16(ONFI_CRC_BASE, (u8 *)&p[i], 254) == le16_to_cpu(p->crc)) { + if (i) + memcpy(p, &p[i], sizeof(*p)); break; } } if (i == 3) { - pr_err("Could not find valid ONFI parameter page; aborting\n"); - goto free_onfi_param_page; + pr_err("Could not find valid ONFI parameter page\n"); + pr_info("Recover ONFI params with bit-wise majority\n"); + ret = onfi_recover_param(p, 3); + if (ret == 0) { + pr_err("ONFI parameter recovery failed, aborting\n"); + goto free_onfi_param_page; + } } /* Check version */ -- 1.7.9.5
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